Hi J H,
from technical point of view, you can use Opentext Archive Server. Basically it's the same procedure like in ECC (create content repository in OAC0, customize SARA, ...).
But, as Bala recommends, you should use it only for real archiving, i. e. for the technical objects like IDOC or BWREQARCH and maybe application data if you do not need online access to the archived data.
Otherwise NLS is better.
Regards,
Benedikt